Screening for cancer can be lifesaving in otherwise healthy at-risk patients. While screening tests lead to a mortality benefit which emerges years after the test is performed, they expose patients to immediate potential harms. In general, patients with metastatic cancer have competing mortality risks that would outweigh the mortality benefits of screening as demonstrated in healthy patients. In fact, patients with metastatic disease may be more likely to experience harm since patients with limited life expectancy are more likely to be frail and more susceptible to complications of testing and treatments. Therefore, the balance of potential benefits and harms does not favor recommending screening for a new asymptomatic primary malignancy in most patients with metastatic disease. Screening may be considered in a very small subgroup of patients where metastatic disease is relatively indolent, or its treatment is expected to result in prolonged survival.
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